It is well known to use visual light signals on law enforcement vehicles, emergency vehicles, tow trucks or the like for increasing the visibility of these vehicles to motorists and pedestrians in emergency and traffic control situations. One of the most common types of light signals is a light bar. Light bars are typically mounted to the exterior roof or top of the emergency or law enforcement vehicles. Alternatively, light bars may be mounted within the interior of these vehicles such that they are visible through the front, side or rear windows.
Generally, light bars may be illuminated by utilizing light sources, such as a plurality of light emitting diodes (LEDs) or halogen lamps to produce different light signals. These light signals may include different colors and/or illumination patterns. The variety of light signals, colors and patterns are useful for generating different visual displays depending on the particular traffic control or emergency situation. As a result, motorists or pedestrians approaching these vehicles may easily view the light display and understand the particular situation based upon the signal, color or pattern being displayed.
In one arrangement, the light bar located on the roof or within the rear window of the vehicle, may display a single color (i.e., red or blue) or a multiple color (i.e., red and blue) warning signal. Once a law enforcement or emergency vehicle stops a target or reaches the scene of a vehicular accident, the operator (i.e., police officer, paramedic or tow truck operator) may activate the light bar to generate the warning signal from the vehicle. In the single color arrangement, the light bar features a single row of LEDs. Alternatively, in the dual color arrangement, the light bar typically consists of two stacked rows of LEDs. Effectively, there are at least two rows or columns of multiple different colored LEDs (i.e., one row contains a plurality of LEDs capable of displaying a first color and the other row contains a plurality of LEDs capable of displaying a different second color). Generally, the colors of the LEDs may be red, blue, amber, or white/clear.
Each row of LEDs disseminates light through an optic or lens (i.e., separate optics or lens are required for each LED and row), essentially two different optics or lens in one light source. In other words, there must be at least two different LEDs corresponding to each optic or lens to produce the different colored pattern (i.e., one LED produces red while the second LED produces blue). The operator also has the option of choosing either top or bottom clusters to select the color or select a random pattern, which will alternate between the two rows/colors or flash both sequentially.
In another arrangement, the light bar is equipped with LEDs that are capable of producing illuminated directional functions, such as an “arrow stick.” In use, the light bar displays the arrow stick configuration, which is typically a single color, such as amber. The pattern displayed is the sequential illumination of the LEDs in the light bar in one direction or the other to direct drivers to one side of the road or the other. When a law enforcement officer reaches a traffic accident on the right side of the highway, the light bar may be used to produce the arrow stick to direct other drivers to the left lanes of the highway. Alternatively, the arrow stick is also capable of being operated to direct drivers to the right lanes of the highway or “center out” (such as when there is an accident or delay in the middle lane of the highway).
The primary disadvantage with the above-identified type of light bars is that they are limited to a single function. Specifically, the light bar may be used only in either warning/emergency mode with a multiple color (i.e., red and blue) illumination pattern or traffic direction mode with a single color (i.e., amber) illumination pattern. Clearly, law enforcement officers and other emergency personnel encounter different traffic control and emergency situations, which necessitate the use of different light signals of varying colors and patterns.
One common approach to the above-identified problem is to install multiple light bars on the law enforcement or other emergency vehicle. For example, an exterior first light bar may be positioned on the roof of the vehicle for producing a red and/or blue emergency signal and an interior second light bar may be positioned in the rear window for producing various amber-colored traffic signals. Of course, the use of multiple light bars is necessarily more expensive due to the purchase and installation costs associated with each light bar. In addition, the installation of multiple light bars is often difficult due to the limited amount of space in and around the emergency vehicle. Finally, each light bar usually requires its own controller/operator unit to control the light bar, which increases the complexity of the installation and operation of the multiple light bars.
An alternative to using multiple light bars is a light bar having multiple LEDs with different banks or rows/columns of different colored LEDs. The different colored LEDs operate independent of each other in single color modes. As a result, a single light bar is capable of producing multiple different colors based on how many different colored LEDs are used. Although this type of light bar is capable of producing different colors and, in turn, different illumination patters, it suffers from certain limitations. Specifically, the light bar requires a greater number of LEDs (i.e., if the light bar produces red, blue and amber colored patterns, there must be multiple red, blue and amber LEDs) than other single color light bars. Further, due to the large number of LEDs, the light bar is more expensive to manufacture and the particular arrangement (i.e., banks or rows) of LEDs contributes to a larger and bulkier light bar that is difficult to install. Finally, if a smaller light bar is desired to minimize the cost of the light bar or is required due to the size constraints of the particular vehicle, fewer LEDs must be used. Consequently, the light output of the light bar is compromised and the warning signal is less effective.
Accordingly, there is a need for a light bar for use in a law enforcement vehicle, emergency vehicle, tow truck or the like that is capable of displaying multiple colors and patterns corresponding to different emergency and warning signals. Namely, the light bar should be capable of producing a multiple color and pattern emergency/warning signal and a single color traffic direction signal through a single optical lens. The light bar should include a plurality of LED packages aligned in a single row wherein each individual diode is capable of changing color. As a result, the light bar can be made smaller and more efficient in terms of cost and complexity to manufacture without losing any light output strength.